Rails runs this file through ERB when loading it, to allow various dynamic options. Heroku make use of this, producing an ERB file that read the DATABASE_URL environment variable and creates the approppriate .yml file pointing to that database.

I’m assuming that in the case of Bamboo the database.yml that was created was a plain Yaml file pointing to your database (I can’t find any reference).

To get your app working on Cedar, you need to run the file through ERB in the same way as Rails does. Change this: